when the price is falling like this then we have to buy as much as possible, so when the bull run occurs we will get huge profit.
This time no one is sure about the bull run because market falling day by day, so buy on this dip on your risk and invest amount which you can afford to lose. Bitcoin is unpredictable so no one exactly knows the future of bitcoin in 2019 but rough guesses for the first quarter of 2019 is that bitcoin will reach 10k$-15kk$